Perissodactyla: An order of ungulates having an odd number of toes, including the horse, tapir, and rhinoceros. (Dorland, 27th ed)ArtiodactylaCetacea: An order of wholly aquatic MAMMALS occurring in all the OCEANS and adjoining seas of the world, as well as in certain river systems. They feed generally on FISHES, cephalopods, and crustaceans. Most are gregarious and most have a relatively long period of parental care and maturation. Included are DOLPHINS; PORPOISES; and WHALES. (From Walker's Mammals of the World, 5th ed, pp969-70)Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.